Alternating-current meter.



No. 7|2,742. Patented-Nov. 4, I902.

E. THOMSON. ALTERNATING CURRENT METER.

(Application filed Apr 10, 1901.)

(No Model.) 2 Sheets-Sheet I Fig.1.

- I C2 c I M2 C C3 WiKnesses. lnvenifor: I y ElihuThomson M a by 45 THEuonms wrrzns co, PHOTO-LIYNCL. WASHINGTON. n. c.

No. 712,742. Patehted' Nov. 4, I902.

. E. THOMSON.

ALTERNATING CURRENT METEB.

(Application filed Apr. 10, 1901.)

2 Sheets-sheaf 2.

(No Model.)

invenCor. Elihu Thomson Elmira Stamps 'ArnNr Fries.

ELIHU THOMSON, OF SVVAMPSCOTT, MASSACHUSETTS, ASSIGNOR TO GEN- ERALELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ALTERNATlNG-CURRENT METER.

SPECIFICATION forming part of Letters'Patent No. 712,742, dated November4, 1902.

Application filed April 10, 1901. Serial No. 55,155. (No model.)

To atZZ whmn it may concern- Be it known that I, ELIHU THOMSON, acitizen of the United States, residing at Swampscott, county of Essex,State of Massachusetts, have invented certain new and usefulImprovements in Alternating-Current Meters, (Case No. 1,507,) of whichthe following is a specification.

My invention relates to alternating-current induction-meters, and hasfor its object to produce a wattmeter of simple and compact constructionembodying a novel and efficient means for generating a shifting field toactuate the short-circuited member or armature of the meter in such amanner as to produce. a correct registration of the energy consumed inthe circuit to which the meter is connected. The construction which Ihave devised combines in a single structure both the shunt and theseries magnet systems.

In the accompanying drawings, which illustrate an embodiment of myinvention, Figure 1 shows the essential elements of a meter having itsfield-magnet system constructed according to my invention, themeter-winding being suitably connected to the source of supply and tothe load. Fig. 2 is a diagram of the f eld-magnet system, showing thearrangement of the coils of a single winding which serves at the sametime both as the series and the shunt winding of the meter. Figs. 3 to6, inclusive, are diagrams illustrating the changes which take place inthe magnetization of the field-magnet system during one complete cycle.

Referring first to Fig. 1, A B indicate the mains of analternating-current-supply system. L indicates the translating'devicesto which current is to be supplied. Interposed between the supply-mainsA B and mains E F, to which the translating devices constituting theload are connected, is the meter M. This meter, as shown, comprises adisk armature D, mounted on a shaft suitably geared to a registeringmechanism R. A retardingmagnet G' is mounted so that its poles include aportion of the disk.

The novel magnet system which constitutes the subject-matter of mypresent invention comprises two peculiar electromagnets M and M suitablypositioned with respect to the meter-disk at a point removed from the infiuence of the retarding-magnet. This fieldmagnet system serves toproduce a rotation of the meter-disk proportional to the consumption ofenergy in the main circuit. The core of each of the separate magnets Mand M is preferably laminated and is provided with three polarprojections, and the two magnets are mounted so that their correspondingpolar projections face each other on opposite sides of the meter-disk.The magnets are provided with a single winding comprising the four coilsC, 0*, C and 0 connected in a closed circuit by the conductors 2 to 7,inclusive. This winding serves at the same time both as the shunt andthe series winding of the meter, the connect-ions of the shunt orpotential circuit being made at the junctionpoints of the conductors 2and '3 and 4: and 5, and the series circuit connections being made onthe one side between the coils C and C and on the other at the junctionof the conductors 6 and 7. As will be seen from an inspection of thediagram in Fig. 2 of the drawings, the coils C and C are wound in thesame direction and connected, so that they form a continuous winding,connected at either end to the conductors 2 and 4, respectively. Thecoils C and C are each wound in the reverse direction to the coils Cand'C and instead of being connected directly in series between theconductors 3 and 5 they are reversely connected, so that the circuitfrom the conductor 3 passes through the coil 0, and thence throughconductors 7 and 6 to coil C and through it to the conductor 5. Thedirection of winding the coils and the connections shown are of coursemerely relative, it being quite immaterial what the direction of windingof the coils may be so long as the circuit connections are so made thatthe coils will produce the same effect as in the arrangementillustrated.

In order that the meter may correctly register the energy consumed inthe circuit to which it is connected, it is essential that the potentialand series currents on non-inductive load be displaced in phase bysubstantially ninety degrees. Figs. 1 and 2 of the drawings show onearrangement which may be used for securing this result. In thisarraugement the potential current is obtained by induction from ahighly-inductive primary 1) of a transformer T, connected to the sourceof supply to which the meter is connected, so that the conductors whichsupply current to the potential and load circuits, respectively, are notconnected directly to the same source, but instead are indirectlyrelated through the windings of the transformer. The transformer isshown connected on the load side of the meter, and this connection is ingeneral the most convenient one; but it may evidently be connected tothe source at any desired point. As a means for producing the desiredphase relation between the shunt and series currents I have indicated aninductive resistance I in the secondary circuit of the transformer; butany suitable phase-displacing means may be used in place of theparticular one illustrated, it being essential only that the current inthe potential circuit be displaced in phase by ninety degrees from theelectromotive force impressed on the metercircuit, or, what amounts tothe same thing, from the current in the series circuit or noninductiveload. The direction in which the turns of the meter-coils are wound andthe connections between the same and the secondary of the transformer Tare such that at any one instant opposite polarities are produced in theprojections facing one another at the ends of the magnets M and M therelative directions of current-flow in the several sections of thewinding being indicated by the light-line arrows adjacent to the turns.Thus the upper magnet may have at one instant a south pole at the leftand a north pole at the right, while the lower magnet at the sameinstant will have a north pole at the left and a south pole at theright, assuming no interference by current in the series winding. Thiscondition I have indicated by the lightline letters N and S in Fig. 2.Assuming that the magnets M and M are energized, as above indicated, thepoles alternating from instant to instant, if a load is put upon themeter by closing the circuit to translating devices L the flow ofcurrent in the series windings, as indicated by the heavy-line arrows inFig. 2, will be in such a direction as to produce consequent poles ofopposite sign at the middle projections g and h of the magnets. Thus theupper magnet may have at one instant a south pole at the projection g,while the lower magnet at the same instant will have a north pole at theprojection h, the end projections of the upper magnet at this sameinstant being both north poles and the end projections of the lowermagnet both south poles. This I have indicated by the heavy-line lettersS and N in Fig 2.

It will of course be understood that the shunt and series magnetizationsindicated in Fig. 2 do not both have a maximum value at the sameinstant, but that one is at a maximum when the other has a zero value.Also it is to be noted that the windings are so arranged and connectedthat the series current will not induce any electromotive force in thepotential circuit, the coils being so connected that the electromotiveforces generated by induction due to the series current constitute abalanced system in so far as the potential circuit is concerned, andvice versa. The eflect of the fluxes produced by the shunt and seriescurrents is to cause a rotation of the meter-armature in a directiondepending upon the direction of the currents relative to each other inthe potential and series circuits. This effect may perhaps be bestunderstood from an inspection of the diagrams in Figs. 3 to 6,inclusive. Fig. 3 is a diagram showing the arrangement of the poles inthe fieldmagnet system at that instant in the cycle of alternation whenthe current in the series circuit is at a maximum and the current in thepotential circuit zero. The diagram of Fig. 4 shows the arrangement ofthe poles ninety degrees later in the cycle when the series current hasfallen to zero and the potential current has risen to its maximum value.The diagram of Fig. 5 shows the arrangement of the poles another ninetydegrees later in the cycle, the current in the series circuit having nowreached its maximum negative value and the potential current havingagain fallen to zero. Fig. 6 shows the arrangement of the poles atapoint in the cycle ninety degrees later than that indicated in Fig.5,when the potential current has reached its maxi mum negative value andthe series current is again zero. From an inspection of these diagramsit will be noted that the field shifts from one polar projection toanother as the current alternates in such a manner that the currentsgenerated in the armature by the flux passing through one set of polesare a moment later attracted or repelled, as the case may be, by thefluxes between another set or sets of poles. For example, the currentgenerated in the armature by the flux through the intermediate polesunder the conditions illustrated in Fig. 3 is a moment later attractedby one set and repelled by the other of the poles shown in Fig. 4, thecurrents generated in the armature by the flux indicated in Fig. t beinga little later attracted on one side and repelled on the other by theintermediate poles shown in Fig. 5. The attractions and repulsions arein such a direction as to produce a continuous rotation in the samedirection, or, in other words, the fluxes may be said to change frommoment to moment in such a manner as to produce a continuous shifting ofthe magnetic field in the same direction in a single field-magnetstructure. Since the potential current is displaced by substantiallyninety degrees behind the impressed clectromotive force, the torqueproduced on the meter-shaft will, as is well understood, vary directlywith the energy consumed by the load, and by the use of a suitablerecording mechanism the meter may be caused to correctly register theenergy consumed.

While I have shown the magnets M and M wound with a single Winding,there is nothing to prevent the use of separate windings for the shuntand series circuits if such an arrangement is deemed desirable. In thiscase the meter-windings would still have a common magnetic circuit,although the shunt and series currents would flow in different paths.

I have not attempted in the present application to illustrate a completemeter structure having all its parts suitably supported from a commonframe, since my invention relates only to the actuating field-magnetsystem and may be applied to any of the existing meter structures. Theactuating fieldmagnet system I have illustrated in its preferred form;but I desire itto be understood that I am not limited to the specificform shown, and I aim to cover in the claims hereto appended allmodifications which embody the essence of my invention.

WVhat I claim as new, and desire to secure by Letters Patent of theUnited States, is-

1. In an alternating-current induction-me-- ter, a field-magnetsystemprovided with a single winding connected to both the series and thepotential circuits.

2. In an alternating-current induction-meter, a field-magnet systemprovided with a single closed winding connected and arranged to serve atthe same time as the series and the potential winding of the meter.

3. In an alternating-current meter, a fieldmagnet system provided with asingle winding consisting of a plurality of coils connected to form aclosed circuit and separate series and potential circuits connected tosaid winding. 7

t. In an alternating-current induction-meter, a field-magnet systemprovided with a single winding consisting ofapluralityofcoils connectedto form a closed circuit, and connections from said single winding to aseries and to a potential circuit, the said connections being soarranged that the electromotive forces induced in said winding, due tothe series current, constitute a balanced system in so far as thepotential circuit is concerned, and vice versa.

5. In an alternating-current induction-meter, a field-magnet systemprovided with a single winding adapted to serve both as a series and asa potential winding, conductors directly connecting said winding to analternating-current source and to the load, and other conductorsconnecting the same winding to a source of potential inductively relatedto the said alternating-current source.

6. In an alternating-current induction-me-- ter, a field-magnet systemprovided with a single winding adapted to serve both as a series and asa potential Winding, and means for causing the current in the potentialcircuit to be displaced by substantially ninety degrees from the currentin the series circuit, on non-inductive load.

7. In an alternating-current ind uction-meter, a field-magnet systemprovided with ya single winding adapted to serve both as a series and asa potential winding, a load-current circuit, and a potential circuitconnected to said single winding.

8. In an alternating-current induction-meter, a field-magnet systemprovided with a single winding adapted to serve both as a series and asa potential winding, a load-current circuit and a potential circuitconnected to said single winding, the said circuits being connected tosources inductively related to one another.

9. In an alternating-current induction-meter, a field-magnet systemprovided with a single winding adapted to serve both as a series and asa potential winding, a load-current circuit and a potential circuitconnected to said single winding, the said circuits being connected tosources indirectly related to one another.

10. In an alternating-current induction-meter, a field-magnet systemcomprising two similar magnet-cores, each having polar projections atitsends, and anintermediate polar projection between the end projections, asingle winding comprising two coils on each of therefrom both to apotential and to a series circuit, the said coils being so connected andarranged that the potential current operates to magnetize the endprojections only of the magnet-cores and the series current to producemagnetic poles at the intermediate projections.

11. In an alternating-currentinduction-meter, a fieldmagnet systemcomprising two similar magnet-cores, each having polar projections atitsends, and an intermediate polar projection between the end projections,a single winding comprising two coils on each of said magnet-cores,conductors uniting said coils in a closed circuit, a series circuitconnected to the points between the two coils of each magnet core, and apotential circuit connected to the points between two coils on differentmagnet-cores, the said coils being so connected and arranged that thepotential current operates to magnetize the end projections only of themagnet-cores and the seriescurrent to produce magnetic poles at theintermediate projections.

12. In a field-magnet system for an alternating-currentinduction-meter,acore of magnetic material having polar projectionsat its ends and an intermediate polar projection between the endprojections, coils thereon connected to potential and series circuits,the coils being so Wound and the connections so arranged that thepotential current Will create opposite polarities in the endprojections,and the series current a pole at the intermediateprojection.

13. In an alternating-currentinduction-meter, two similar cores ofmagnetic material having polar projections at their ends, and anotherpolar projection at a point intermediate thereof, the said cores beingmounted so that the fluxes between their corresponding polar projectionswill intersect the meterarmature, and coils on said cores connected topotential and series circuits in such a manner that the potentialcurrent will generate a flux flowing in a path through the endprojections of the two cores, and the series current a flux flowing in apath through the intermediate projections of the two cores.

14. In an alternating-currentinduction-meter, two similar cores ofmagnetic material having polar projections at their ends, and anotherpolar projection at a point intermediate thereof, the said cores beingmounted so that the fluxes between their corresponding polar projectionswill intersect the meter-armature, coils on said cores connected tovpotential and series circuits in such a manner that the potentialcurrent will generate a flux flowing in a path through theendprojections of the two cores, and the series current a flux flowing in apath through the intermediate projections of the two cores, and a meansfor causing the shunt-flux to be displaced by ninety degrees from theflux due to the series Winding on non-inductive load.

In witness whereof I have hereunto set my hand this 6th day of April,1901.

ELII'IU THOMSON.

Witnesses:

DUGALD MoK. McKILLoP, JOHN A. MCMANUS.

